Japanese Patent Laying-Open No. 7-310174 (Patent Document 1) discloses a coating layer made of a composition of (AlxTi1−x−ySiy)(NzC1−z) (where 0.05≦x≦0.75, 0.01≦y≦0.1, 0.6≦z≦1) that is formed on a surface of a base material made of WC-based hardmetal, cermet, high-speed steel or the like, for the purposes of improving wear resistance and surface protecting function of a coated cutting tool, a wear-resistant tool and others.
As the recent trend of coated cutting tools, however, dry processing using no cutting oil solution has increasingly been demanded from the standpoint of protection of global environment, materials to be cut have been diversified, and cutting speed has further been increased so as to improve processing efficiency. Under these circumstances, the cutting edge of the coated cutting tool tends to be subjected to an increasingly higher temperature during the cutting process, which would result in a shorter life of the coated cutting tool. Thus, the requirements in property of the materials for the coated cutting tools have become more and more severe.
Based on the foregoing, for example, Japanese Patent Laying-Open No.2004-169076 (Patent Document 2) discloses a coating layer made of a composition of (AlxCr1−x) (N1−α−β−γBαCβOγ) (where 0.45<x<0.75, 0≦α<0.12, 0≦β<0.20, 0.01≦γ<0.25) aiming at improving wear resistance, adhesion and wear resistance. Further, Japanese Patent Laying-Open No.2003-34859 (Patent Document 3) discloses a coating layer made of a composition of (Alb, [Cr1−αVα]c) (C1−dNd) (where 0.5≦b≦0.8, 0.2≦c≦0.5, b+c=1, 0.05≦α≦0.95, 0.5≦d≦1) or a composition of (Ma, Alb, [Cr1−αVα]c) (C1−dNd) (where M is at least one kind selected from the group consisting of Ti, Nb, W, Ta and Mo, 0.02≦a≦0.3, 0.5≦b≦0.8, 0.05≦c, a+b+c=1, 0.5≦d≦1, 0≦α≦1).
Patent Document 1: Japanese Patent Laying-Open No. 7-310174
Patent Document 2: Japanese Patent Laying-Open No. 2004-169076
Patent Document 3: Japanese Patent Laying-Open No. 2003-34859